Two-Photon Sequential Absorption Spectroscopy of Isotopic Species of Iodine and Related Interhalogens

Abstract

<p>Two-photon sequential absorption spectroscopy has been used to study the isotopes of the following diatomic molecules: iodine, ¹²⁷I₂ and ¹²⁹I₂; iodine monochloride, I³⁵Cl and I³⁷Cl; and iodine monobromide, I⁷⁹Br and I⁸¹Br. The interhalogens were studied via these methods with no special purification or isotope enrichment. Spectra of each isotope individually could be obtained.</p> <p>In iodine the B state potential function at large internuclear separation and the B state dissociation limit were examined using a combined isotope, mass-scaled version of Le Roy's long-range potential theory. The absolute vibrational numbering and molecular constants were determined for 4 excited g states in the 5eV region of both isotopes. The E state of iodine was measured in sufficient detail in both isotopes to allow calculation of an RKR potential for this state. The fluorescence lifetimes and the effects of self-quenching and foreign-gas quenching were also measured in these high lying excited states in a preliminary fashion.</p> <p>In the interhalogens, ICl and IBr, single excited states in the 5eV region were observed. Isotopic data were used to determine the absolute vibrational numbering and thus good molecular constants for these states. The intermediate B' state of IBr was partially measured under high resolution as a necessary prerequisite for the study of the higher lying excited state.</p>